Data is written on a magneto-optic or optical disk by placing a small spot of light on the magneto-optic or optical layer on the surface of the disk. The smaller the spot of light, the more data that may be written per unit area on the disk. Thus, there is incentive to create a smaller, more focused spot on the magneto-optic optical layer of the disk.
As an example, a head slider with a refractive lens flies above a magneto-optic disk which is mounted on a spindle driven by a motor to rotate the disk at high speed. The head slider flies over the surface of the disk in a manner similar to a read/write head, as described in U.S. Pat. No. 5,497,359, to H. Mamim et al., issued on Mar. 5, 1996. The refractive lens focuses light from a laser into a spot on the surface of the disk. FIGS. 1A and 1B show a head slider 10 with a refractive lens 12. Head 10 has an air bearing surface 14 that provides the necessary lift to head 10 as it flies above the disk.
As another example, an optical mechanical assembly ("OMA") with a refractive lens, such as the type used in compact disk drives or magneto-optic devices, remains at a constant height above a rotating disk. FIG. 2 shows an OMA 16, with refractive lens 18, positioned on an actuator carriage device 20 over an optical disk 22, such that OMA 16 is at a fixed height over optical disk 22. Refractive lens 18 focuses light onto a spot on the surface of disk 22.